Many studies have shown the soil gas method to be one of the most reliable investigation tools in the research of earthquake precursory signals and fault delineation. The present research is aimed finding the relationship between soil gas distribution and tectonic systems in the vicinity of the Hsinhua Fault zone in the Tainan area of Southern Taiwan. More than 110 samples were collected along 13 traverses to find the spatial distribution of Rn, He, CO(2) and N(2). The spatial congruence of all the gases shows that N(2) is the most probable carrier gas of He, whereas CO(2) seems to be a good carrier gas of Rn in this area. From the spatial distribution of Rn, He, CO(2) and N(2) the trace of Hsinhua Fault and neotectonic features can be identified. The spatial distribution of studied gases shows a clear anomalous trend ENE-SWS along the Hsinhua Fault. (C) 2010 Elsevier Ltd. All rights reserved.